The present invention relates to a method for the qualitative and quantitative determination of the hydrogen isotopes, protium, deuterium and tritium, in a sample that may contain hydrogen, water or a mixture thereof, by means of microwave spectrometry and to a system for implementing the method.
Large quantities of tritium and deuterium are used in nuclear fusion experiments. Water samples containing hydrogen isotopes in greatly varying concentrations must be analyzed. In normal water vapor the percentage of water vapor which contains deuterium and tritium may lie in the ppb or ppm range, but it can also reach up to 100%.
The known detection methods operating with a counting tube or liquid scintillator cannot be used to test samples from nuclear fusion experiments because other .beta.-radiators interfere with the tests and inactive hydrogen isotopes, protium and deuterium, cannot be detected.
Microwave spectroscopy is generally known, as discussed in "Microwave Spectroscopy of Gases" by T. M. Sugden and C. N. Kenney, 1965, D. VanNostrand Comp., included herein by reference, as is its use for the determination of the structure of molecules, their bond spacing and bond angles. Moreover, the microwave spectrum of the hydrogen compounds H.sub.2 O, D.sub.2 O, T.sub.2 O, HDO, HTO and DTO in a range between 10 GHZ and 300 GHz is known, as disclosed in Physical Review A, Volume 5, 1972, page 487, by DeLucia, Helminger, Cook and Gordy, in Volume 8, 1973, pages 2785-2791 and Volume 10, 1974, pages 1072-1081, by Helminger, DeLucia and Gordy, also included herin by reference.
The microwave spectrum of the hydrogen compound D.sub.2 O is known, as disclosed in J. Chem. Phys. 53, 1970, page 2565, by Benedict, Clough, Frenkal and Sullivan and for HDO in J. Chem. Phys. 55, 1971, page 5334, by DeLucia, Cook, Helminger and Gordy.
Teflon.RTM., which is customarily used as a supporting structure of the Stark electrode in the measuring cell of a microwave spectrometer, absorbs tritium in hydrogen as well as in water form, which negatively influences the lower detection limit. Accordingly, conventional measuring cells cannot be used for detecting and quantifying isotopes of hydrogen.